Question

For a first order reaction $A → B$, the rate constant, $k = 5.5×10^{–14}s^{–1}$. The time required for 67% completion of reaction is $x×10^{–1}$ times the half life of reaction. The value of $x$ is _____. (Nearest integer)

Answer 1

$∵ kt = ln \frac {A_0}{A}$

$\frac {ln2}{t_{\frac 12}}$ $t$67% $=ln\frac {A_0}{0.33A_0}$
\frac {log\ 2}{t_{\frac 12}}$$t67% = $log \frac {1}{0.33}$
$t$67% $= 1.566 t_{\frac 12}$
$x = 15.66$
Nearest Integer $= 16$

So, the answer is $16$.